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Variable structure adaptive control of robot manipulators

Yu, H.; Lloyd, S.


S. Lloyd


The two main problems with variable-structure control are control input chattering and the assumption of known parameter uncertainty bounds, the second of which is studied. The robustness of a recently proposed variable-structure control approach with estimated bounds algorithm 1 in the paper is first examined. Stability analysis of the proposed variable-structure adaptive control schemes is establislied in the Lyapunov sense. To improve robustness of algorithm 1, four new algorithms are proposed and a comparative study of these is presented. Algorithm 1 performs well without the other uncertainty disturbances except parameter uncertainty. However, it may lead to an unstable system if input disturbances exist. Algorithm 2 requires the upper bounds of the uncertainty parameters. Algorithm 3 has a good performance on robustness to input disturbances besides parameter uncertainty. However, the tracking errors of algorithm 3 do not converge to zero even without input disturbances. To improve this, two modifications of algorithm 3 are proposed. Algorithm 4 has good tracking performance and robustness but requires knowledge of the parameter uncertainty bounds. Algorithm 5 gives better tracking performance and using the same kinds of previous knowledge as in algorithms 1 and 3. Robustness of the proposed algorithms to input disturbances is investigated. Extensive comparative simulation results are presented to support the theoretical analysis of the paper.

Journal Article Type Article
Publication Date 1997-03
Deposit Date Jun 18, 2022
Journal IEE Proceedings - Control Theory and Applications
Print ISSN 1751-8644
Electronic ISSN 1751-8652
Publisher Institution of Engineering and Technology (IET)
Peer Reviewed Peer Reviewed
Volume 144
Issue 2
Pages 167-176
Public URL